In recent years, there has been an increase in need for high density mounting of wires of a semiconductor element and a display element of a liquid crystal display, a touch panel, and the like as well as high density mounting of connection terminals such as bumps. Therefore, the miniaturization of the wires and the connection terminals is accelerating to allow high density mounting. Consequently, a resist pattern used in formation of the wires, the bumps, or the like has been required to be miniaturized.
Generally, the wires, the bumps, and the like are formed by forming a resist pattern on a substrate having a metallic foil such as a copper foil and then using the thus obtained resist pattern as a mask for performing plating, etching, or the like. The resist pattern is generally formed by applying a photosensitive resin composition to the substrate and then exposing and developing the resin coating. As the photosensitive resin composition, a radical negative-type photosensitive resin composition containing a photo-radical initiator is commonly used. In the photosensitive resin composition, radicals act as active species. Thus, improvement of the pattern resolution is limited because of inhibition by oxygen contained in the air. In particular, miniaturizing of the resist pattern causes a problem that the top of the obtained resist pattern is rounded and a resist pattern having a rectangular cross section cannot be obtained, resulting in deterioration of resolution.
In addition, in cases where the resist pattern is miniaturized, the contact area between the resist pattern and the metallic foil becomes narrow. Thus, insufficiency of adhesiveness between the resist pattern and the metallic foil can cause a problem that the resist pattern collapses.
In Patent Document 1, as a composition providing a resin pattern which demonstrates favorable adhesiveness to a metallic film, a photosensitive resin composition comprising an alkali-soluble resin produced by a reaction between an acid radical-containing acrylic resin and an alicyclic epoxy group-containing unsaturated compound (A); a polyfunctional monomer having three or more functional groups (B); a nitrogen-containing monofunctional monomer (C); and a photo polymerization initiator (D) is disclosed. However, under the miniaturization of the resist pattern, it is difficult for even the resin pattern obtained from this composition to ensure favorable adhesiveness to the metallic film.